Projectile firing device



Feb. 28, 1967 JEAN-JACQUES GRIESSEN 3,305,163

PROJECTILE FIRING DEVICE 5 SheetsSheet l Filed July 29, 1964 Feb. 23, 1967 JEAN-JACQUES GRIESSEN 3,395,163

PROJECTILE FIRING DEVICE 5 Sheets-Sheet 2 Filed July 29, 1964 InvEm-o Jean u es Gvess 6h i )s inw..

Feb- 28, 1967 JEAN-JAcQuEs @HESSENv 3,305,163

PROJECTILE FIRING DEVICE` Filed July 29, 41964 5 sheets-sheet s HTToRnEy Feb- 28, 1967 JEAN-JACQUES GRIESSEN PROJECTILE FIRING DEVICE Filed July 29, 1964 5 sheets-sheet 4 HTTOQEY Feb. 28, 1967 JEAN-JACQUES GRIESSEN PROJECTILE FIRING DEVICE 5 Sheets-Sheet 5 Filed July 29, 1964 United States Patent O 3,306,163 PROJECTILE FIRING DEVICE .lean-Jacques Griessen, Geneva, Switzerland, assigner to Transurvey Holding Company, Inc., Societe Anonyme, Panama, Panama Filed .Iuly 29, 1964, Ser. No. 385,859 Claims priority, application Switzerland, May 12, 1964, 6,178/64; May 27, 1964, 6,936/64 8 Claims. (Cl. 89-1) The present invention relates to projectile tiring devices of the type comprising a guide rod, a striker subjected to the action of yan instantaneous release propulsion device, a hollow body fitting slidably on the guide rod, and a piston head tting in the bore of the hollow body so as to form in said bore an extensible explosion chamber in which a firing charge is disposed.

The device according to the invention is characterised in that the liring charge is disposed in the case of an auxiliary projectile housed in said explosion chamber, and in that the hollow body is provided with at least one radial aperture permitting the escape of the explosion gases yof the auxiliary projectile charge, the whole device being so shaped and disposed that the hollow body or the guide rod is projected by the auxiliary projectile when the charge contained in its case explodes, and that the gases of this explosion escape through said radial aperture only when one of the two parts, the guide rod or the hollow body has travelled a distance in relation to the other such that the radial aperture of the hollow body is situated between the case and the wall of the auxiliary carrier projectile.

'Ihe accompanying drawing illustrates diagrammatical- 1y by way of example various forms of construction of the projectile tiring device forming the subject of the invention.

FIGURES 1 to 4 relate to a iirst embodiment.

FIGURE 1 is a view in axial section thereof;

FIGURES 2 and 3 are partial view in axial section thereof, on a smaller scale and in two successive phases of the firing and,

FIGURE 4 is a view in elevation of an alternative embodiment.

FIGURES 5 to 9 relate to a second form of construction of the projectile tiring device according to the invention FIGURE 5 is a general view thereof in axial section with the projectile to be tired in the position occupied on the firing of the shot;

FIGURE 6 is a partial view thereof in axial section with the projectile to be tired in the position which it occupies at the moment when it leaves the device;

FIGURE 7 is a general view thereof in elevation on a reduced scale;

FIGURES 8 and 9 are axial sections on a larger scale of the percussion device and of the piston head respectively;

FIGURES 10 to 14 relates to a third form of construction of the device according to the invention;

FIGURE l is a general view thereof in axial section similar to FIGURE FIGURE l1 is a partial view in axial section similar to FIGURE 6;

FIGURE l2 is a general view thereof similar to FIG- URE 7;

FIGURE 13 is la partial axial section on a larger scale of the percussion device, and

FIGURE 14 is an axial section on a larger scale of the piston head.

The projectile tiring device illustrated in FIGURES 1 to 4 comprises a hollow guide rod 1 closed at its rear end, which is iirmly held in a sleeve 2 supported by a fixed support. This closed rear portion of the guide rod l contains a slidable striker 3 acted on by a pre-armed spring 4 and retained by a catch constituted by a radial pin 5. The mouth of the guide rod 1 is capped by a solid metal cap 6 placed over the end of the tube 1 and having an `axial hole 7 of the same diameter as the pin 3a of the striker. The projectile to be red is engaged on the front and middle portion of the hollow rod 1 carrying the cap 6. This projectile comprises a hollow cylindrical body 8, the cylindro-conical head Sa of which is closed, and the open rear end of which is integral with a metal ring 9 fitting slidably on the hollow rod 1. The middle portion of the hollow body 8 is tted to slide fluid-tightly on the cap 6, which thus forms a piston head. The bore in the hollow body 8 has at its front end, in front of the cap 6, a portion 10 of slightly reduced diameter forming an explosion chamber containing a small auxiliary propectile comprising an unarrnoured ball 11 held by crimping in a case 12 containing an explosive charge.

In its middle portion the hollow cylindrical body 8 has a ring of radial apertures 13 bringing the bore into communication with an external decompression chamber 14 provided between the wall of the hollow body 8 and an outside sleeve 15 fixed between two collars 8b and 8c on the body 8. The sleeve 15 is likewise provided with a ring of radial lapertures 16 bringing the chamber into communication with the free atmosphere.

The operation of the device just described is as follows: under the effect of the explosion of the charge contained in the case 12 of the auxiliary projectile (hereinafter referred to as carrier projectile), this explosion being produced by the percussion pin 3a driven forwards by the spring 4 when the catch 5 is drawn outwards, the ball 11 of the small carrier projectile, which when the device is in the position illustrated in FIGURE l touches the solid end of the head 8a of the hollow body 8, drives the latter forwards, the case 12 adhering through the action of the recoil to the cap 6 covering the mouth of the hollaw guide rod 1. During the extremely short time (following the explosion) required by the hollow body 8 to travel the necessary distance to pass from the .position illustrated in FIGURE 1 to that illustrated in FIGURE 2, in which the radial apertures 13 are still masked by the cap 6 or the case 12, the explosion gases cannot escape through these apertures and consequently give up all their energy to the carrier projectile, the thrust applied by which to the body 8 attains a maximum. Continuing its travel, guided on the inside of the hollow rod 1, the hollow body 8 leaves said rod as indicated in FIGURE 3, carrying with it, ,by means of its integral rear ring 9, the cap 6 and the empty case 12; as soon as the radial apertures 13 pass beyond the case 12, the explosion `gases contained in the chamber 10 are admitted through said apertures intoV the decompression chamber 14, where they can expand before escaping to the open atmosphere through the apertures 16. This escape of the gases expanded in the chamber 14 enables the noise produced by the explosion of a small cartridge, which is already relatively small to be reduced. The recoil may be absorbed by a damping support in which the sleeve may be fixed.

FIGURE 4 illustrates an alternative embodiment in which the hollow body is provided with an ogive 18 possessing guide vanes 19 and adapted to contain an explosive, smoke-producing, or tear gas-producing charge, an optical or acoustic signalling device, or any other device operating after a time lag or on impact.

It is obvious that the propulsion device operating the striker may lbe diiferent from that illustrated Iby way of example, and that it could for example be electrical, electro-magnetic, pneumatic, or of another type.

In a modified embodiment (not illustrated), the cappiston head may be integral with the guide rod and said rod may be driven with the hollow body when the ring integral with the latter strikes against the cap 6. In this case the rear end of the hollow guide rod would of course not be fixed in the sleeve 2, but simply laid against a fixed support.

In this case also, the rear end of the hollow guide rod could be open and the propulsion device be independent of said rod and not move with the latter.

The device illustrated in FIGURES 5 to 9 comprises a solid launching and yguide rod 21, the rear end of which is held firmly in a support, which may for example be the muzzle of any firearm, or a support fixed to the ground. On the rod 21 there is slidably fitted the rear -portion 22a of the hollow body 22 of a projectile to be fired, the cylindro-conical head 23 of which may contain an explosive, anti-tank, smoke-producing, tear gas-producing, or lighting charge, a device operating with a time lag or on impact, or else an optical or acoustic signalling device.

By means of a screw fitting 24 the head 23 of the projectile is made fast to the front hollow portion 25a of a percussion rod 25, the rear end of which terminates in a percussion pin 25b. The percussion rod 25 with its pin 25h is mounted slidably in the bore of the front portion 22b of the hollow body 22 through the medium of a threaded metal ring 26 (FIGURE 8). The percussion rod 25 is subjected to the action of a coil spring 28 which surrounds its hollow front portion 25a and bears on the one hand against an inside shoulder 22e provided on the front end 22b of the hollow body 22, and on the other hand against the front face of the ring 26. The solid portion of reduced diameter of the rod 25 and the percussion pin 2519 are guided in a sleeve 2'7 screwed in the middle portion and in the front portion 22b of the hollow body 22. A catch pin 29 (FIGURE 8) penetrating radially into the front portion 22b of the hollow body 22 enables the percussion spring 28 to lbe held armed when the ring 26 is situated in the front of the catch 29, the head 23 of the projectile to be fired having been drawn forwards with the percussion rod 25. The front portion 22h of the hollow body is fixed to the middle portion of the latter through the medium of the sleeve 27 screwed into these two parts.

A piston head 30 fits in the bore of the middle and rear portions of the hollow body 22 formingT a cylinder, so as to slide in a fluid-tight manner therein, and has an axial hole 31 bringing a rear space 32 into communication with a front chamber 33 containing a wad of stiff grease 34. The piston head bears at the rear against the front end of the .guide rod 21, of which an extension 21a having a reduced diameter penetrates with play into the rear space 32. The portion -of the bore in the hollow body 22 which is situated between the front face of the piston head 30 and the rear face of the sleeve 27 forms an explosion chamber containing an auxiliary projectile 35 which, like usual standard ammunition, is composed of a case 35a containing an explosive charge and a cylindro-conical ball 35b of more or less soft metal (not armoured), secured by crimping in the case 35a. When this auxiliary projectile 35 is contained in the explosion chamber lhaving the dimensions possessed by it on the tiring of the shot (FIGURE 5), said projectile practically completely fills said chamber and the conical point of the ball 3511 engages lightly in the front grease chamber 33 of the piston head 30.

The rear portion 22a of the hollow body has in its thin wall a ring of radial apertures 36 bringing the bore of said rear portion into communication with an external decompression chamber 37 which together with said thin wall forms an external sleeve 38 fixed between a rear collar 39 yand an outer rib 40 (FIGURE 6) on the hollow body 22a. This external sleeve 38 may also be provided with radial apertures 41 bringing the decompression chamber 37 into communication with the outside, or in the construction illustrated with an empty space 42 provided between the sleeve 38 `and a tubular support 43 carrying vanes 44 and provided with perforations or longitudinal slots. This support 43 is fixed between the rear collar 39 and a nut 45.

The operation of the projectile firing device which has just been described (FIGURES 5 to 9) is as follows:

In order to load this device, the front portion 22b of the hollow body 22 and also the connecting sleeve 27 are unscrewed in order to free the explosion chamber situated between the piston head 30 and the front end of the middle portion of the hollow body 22, the piston head 3l) being supported against the free end of the guide rod 21. A ball cartridge 35 is then introduced into said chamber with its ball 35a directed towards the rear and bearing by its conical tip against the cylindrical wall of the grease chamber 33 of the piston head 30. The sleeve 27 and the front portion 22b of the hollow body are then screwed back in position, after the head 23 of the projectile to be launched has been pulled forward in order to arm the percussion spring 28, which is held armed by means of the catch pin 29 which bears on the rear face of the ring 26. The front face of the case 35]; of the carrier projectile 35 rests on the rear face of the threaded sleeve 27.

In order to re the shot and project the head projectile 23 forwards, it is suliicient to pull the catch pin 29 in the outward direction in order to free the armed spring 28 and propel towards the rear the percussion rod 25, the pin 25b of which strikes against the case 35b and causes it to explode. The case 35h then acts on the rear face of the sleeve 27 which is integral with the hollow body 22 and propels the latter forwards, while the ball 25a is wedged in the grease chamber 33 of the piston head 30. As it does so, the ball 35a which is of relatively soft metal brakes the recoil as soon as the shot is fired. This braking is accentuated by the wad of grease 34 into which the tip of the ball penetrates. As a result, the grease is pressed through the axial passage 31 in the piston head 30 towards the rear space 32 in the latter, into which the extension 21 of reduced diameter of the guide rod 21 penetrates with play. The grease is spread around this extension and over the rear face of the piston head which surrounds the space 32 and on this annular surface forms a thin damping iilm intended to damp the impact of the piston head against the end of the cylinder when the projectile leaves the guide rod 21. The grease thus not only forms a recoil and impact damper, but also contributes towards sealing the explosion chamber immediately after the firing of the shot. As soon as the hollow body has travelled a suficient distance on the guide rod 21 for its radial apertures 36 to be `situated between the ball and the case of the carrier projectile, the ,gases contained in the explosion chamber, and already partially expanded because of the elongation of that chamber 26 can escape through said apertures and pass into the decompression chamber 37 and thence into the outside space 42 and finally into the atmosphere. Because of this progressive decompression of the explosion gases, and on the other hand because -of the propulsion of the hollow body by the case 35a possessing on the firing of the shot its maximum speed imparted to it by all the energy developed by the explosion of the charge enclosed by the ball secured by crimping in the case, it is possible to obtain with a cartridge of relatively small calibre of a substantially greater propulsion effect than that which would be obtained wit-h a much heavier charge exploding directly in an explosion chamber (for example a blank cartridge). In addition, the damping by the ball acting propressively, starting from the firing of the shot, on the piston head 3i) and the wad of grease 34 contributes towards considerably reducing the recoil effect and the mechanical `stresses on materials used, as well as reducing the noise of the explosion, which is already very small because of the use of a cartridge which is very small in relation to the weight of the projectile to be launched.

The projectile ring device illustrated in FIGURES l0 to 15 is distinguished from that just described in that the Ihollow body is fixed while the guide rod itself is projected by the carrier projectile. The central body of the projectile 80 to be launched, for example of an antitank grenade provided with vanes 81 and carrying in its head 82 an explosive or other charge, is screwed on t'he front threaded end 51a of the guide rod 51. A hollow body 52, the rear portion 52a of which is -held rmly in a support, is fitted slidably by means of a sleeve 53 on the guide rod 51. The middle portion of the hollow body 52 is fixed to a rear extension 52a by means of a sleeve 57 screwed into these two parts. In the xed rear extension 52a of the hollow body there is slidably mounted, through the medium of a threaded ring 54, a percussion rod 55 which ends at the front in a pin 55b and on the hollow rear portion 55a of which there is wound the percussion spring 58 which bears on the one -hand against the spring 54 and on the other hand against an inside shoulder 52b on the rear extension 52a of the lhollow body.

The rear end of the extension 52a of the hollow body is provided with a longitudinal slot 56 engaging a catch pin 59 inserted in the hollow rear end 55a of the percussion rod 55 and intended to keep the percussion spring 58 armed when it is pulled to the rear as far as the rear end of the slot 56 and locked in that position by introducing it by a slight turn into a lateral notch 56a in the wall of the slot 13.

In the bore in the hollow body 52 ahead of the sleeve 57 there is fitted with Huid-tight slidability a piston head 60 having an axial hole 61 bringing a front space 62 into communication with a rear chamber 63 in which a wad of stiff grease `64 is disposed (FIGURE 14). The piston head 63 bears at the front against the rear end of the guide rod 51, of which an extension 51a of reduced diameter enga-ges with play in the front space 62 in the piston head 60. The portion of the bore in the hollow body 52 which is situated between the rear face of the piston head 60 and the front face of the sleeve 57 forms an explosion chamber in which there is received an auxiliary projectile 65 composed, like customary standard ammunition, of a case 65a containing an explosive charge and of a cylindro-conical wall 65h of more or less soft metal (not armoured), secured by crimping in the case 65a. When this carrier projectile is accommodated, with its ball 65b towards the front, in the explosion chamber as the latter is constituted before the tiring of the shot (FIGURE it lls said chamber almost completely and the conical tip of its ball 6519 engaged lightly in the grease chamber 63 in the piston head 60.

The outside portion of the hollow body 52 has in its wall of reduced thickness a ring of radial apertures 66 bringing the bore of said portion into communication with an external decompression chamber formed by said wall together with an external sleeve 68 xed between a collar 69 on the sleeve 53 and an external rib 70` on the .ollow body 52. This external sleeve 68 may also lbe provided with radial apertures, not shown, bringing the decompression chamber 67 into communication with the outside, or when the projectile 80` integral with the guide rod 51 is in the position shown in FIGURE 10 on the tiring of the shot, with the inside empty space 71 in the tubular support 72 which is open at the rear and carries the vanes 81 of the projectile.

The operation of this projectile firing device (FIGURES 10 to 14) is as follows:

In order to load the projectile firing device, the front portion of the hollow body 52 and also the connecting sleeve S7 are unscrewed in order to free the explosion chamber situated between the piston head 60 and the rear end of the middle portion of the hollow body 52, the piston head 60 being supported against the rear end 51b of the guide rod 51. A ball cartridge 65 is introduced into said chamber with its ball 6Sb directed forwards and bearing by its conical tip against the cylindrical wall of the grease chamber 63 in the piston head 60. The sleeve 57 and the middle portion of the hollow body 52 are then screwed in place again and the percussion spring 58 is armed by pulling towards the rear the percussion rod 55 by means of the radial catch pin 59, which is locked, by a slight rotation, in the notch 56a. In order to tire the shot and project the projectile 80, with its head S2 forwards (FIGURE 12), it is sufficient to free the catch pin 59 from the notch 65a in order to free the percussion spring 58 which propels forwards the percussion rod 55, the pin 55b of which strikes the case 65a of the carrier projectile 65 and explodes the charge which it contains, thus propelling the ball 65b which drives forwards the piston head 60 and, through the latter, the guide rod 51 which is integral through its threaded end 51a with the projectile body 8G. The ball 65h is wedged in the -grease chamber 63 and in the latter compresses the grease of the wad 64, part of which passes through the axial passage 61 into the front space 62 and spreads around the extension SIb of the rod 51 and over the front surface of the piston head, where it forms a film which damps the impact of the piston head 60 against the end of the cylinder formed by the sleeve 53, at the moment when the rod S1 with the projectile carried by it leaves the xed hollow body 52. As soon as the guide rod 51 propelled by the piston head 60 under the thrust of the ball 6511 has travelled, in the bore in the hollow body 52, through a suicient space for the radial apertures 66 on said body to be situated between the -ball 65b and the case 65a on the carrier projectile, the gases contained in said space can escape through said apertures and pass into the decompression chamber 67 and thence to the outside through the open rear of the support 72 of the vanes 81.

What I claim is:

1. A projectile firing device comprising:

a cylindrical guide member,

a body member having a cylindrical axial bore in one end thereof extending to a closed end wall, said cylindrial guide member being slidably disposed within said axial bore in a fluid-tight manner,

a piston slidably disposed within said axial bore between said guide member and said closed end wall of said body member and being in contact with said guide lmember, the space between said piston and said closed end wall forming an extensible explosion chamber,

an auxiliary projectile including a cartridge case having an explosive charge and a ball member, said auxiliary projectile being positioned within said extensible explosion chamber in forceful contact with said piston and said closed end wall of said body member,

striker means for exploding the charge in said cartridge case, and said body member including at least one radial aperture communicating with said axial bore at a point spaced from said piston on the side thereof remote from said closed end wall so as to effect communication of said radial aperture with said extensible explosion chamber only at a predetermined time after explosion of said cartridge case.

2. A projectile firing device as defined in claim 1 wherein the body member is provided with an outside sleeve forming a gas decompression chamber, with which said radial aperture is in communication.

3. A projectile firing device comprising a cylindrical guide member,

a body member having a cylindrical axial bore in one end thereof extending to a closed end wall, said cylindrical guide member being slidably disposed within said axial bore in a fluid-tight manner,

a piston slidably disposed within said axial bore between said guide member and said closed end wall of said body member and being in contact with said guide member, the space between said piston and said closed end wall forming an extensible explosion chamber,

an auxiliary projectile including a cartridge case having an explosive charge and a ball member, said auxiliary projectile being positioned within said extensible explosion chamber in forceful Contact with said piston and said closed end wall of said body member, and

striker means for exploding the charge in said cartridge case,

the primary projectile to be fired being integral with the body member on which the auxiliary projectile acts,

said striker means being disposed in the axial bore of the body member forming part of said primary projectile and being directed to strike the cartridge case of the auxiliary projectile,

the ball member of the auxiliary projectile being directed toward the guide member and bearing against the piston closing the explosion chamber,

a sleeve integral with the body member in the axial bore thereof and provided with an axial hole for the passage of the striker means therethrough into contact with the cartridge case of said auxiliary projectile, the striker being propelled by the cartridge case which it has struck together with the sleeve in the primary projectile, while the ball member of the auxiliary projectile is pressed by the recoil against said piston.

4. A projectile firing device comprising a cylindrical guide member,

a body member having a cylindrical axial bore in one end thereof extending to a closed end wall, said cylindrical guide member being slidably disposed within said axial bore in a Huid-tight manner,

a piston slidably disposed within said axial bore between said guide'member and said closed end wall' of said body member and being in contact with said guide member, the space between said piston and said closed end wall forming an extensible explosion chamber,

an auxiliary projectile including a cartridge case having an explosive charge and a ball member, said auxiliary projectile being positioned within said extensible explosion chamber in forceful contact with said piston and said closed end wall of said body member, and

striker means for exploding the charge in said cartridge case, Y

the primary projectile to be fired 4being integral with the guide member on which the auxiliary projectile acts,

said striker member being disposed in the portion of the body member remote from the primary projectile and being directed to strike the cartridge case of the auxiliary projectile, the ball member of which bears against the piston which closes the explosion chamber, bearing against the end of the guide member upon firing of the auxiliary projectile,

a sleeve screwed into the axial bore of the body member and provided with an axial hole for the passage of the striker means, the cartridge case of the auxillary projectile bearing against said sleeve.

5. A projectile ring device as defined in claim 4 wherein the striker means is mounted in a fixed tubular support which is at least detachably secured to the body member.

6. A projectile firing device comprising a cylindrical guide member,

a body member having a cylindrical axial bore in one end thereof extending to a closed end wall, said cylindrical guide :member being slidably disposed within said axial bore in a fluid-tight manner,

a piston slidably disposed within said axial bore between said guide member and said closed end wall of said body member and being in contact with said guide member, the space between said piston and said closed end wall forming an extensible explosion chamber,

an auxiliary projectile including a cartridge case having an explosive charge and a ball member, said auxiliary projectile being positioned within said extensible explosion chamber in forceful contact with said piston and said closed end wall of said body member, and

striker means for exploding the charge in said cartridge case,

the primary projectile to be fired being integral with said body member on which the auxiliary projectile acts,

said piston being provided with a cavity in each end thereof and an axial bore bringing said cavities into communication with one another, one of said cavities receiving the end of the guide member therein and the other cavity being in wedging contact with the ball member on the auxiliary projectile.

7. A projectile firing device as defined in claim 6 wherein the end cavity in the piston in wedging contact with the ball member contains a means for damping the impact of the ball member on the piston and the impact of the piston against the bore of the hollow body upon firing of the projectile, said damping means being in the form of a wad of grease.

8. A projectile firing device as defined in claim 7 wherein said explosion chamber is only very slightly larger than said auxiliary projectile so as to provide said projectile with maximum thrust upon firing and so that the recoil will be immediately damped through the driving of the ball member into the grease wad in the piston.

References Cited by the Examiner UNITED STATES PATENTS 1,721,704 6/1929 Madaschi 239-13 1,900,790 3/1933 Brandt 42 1.2 3,098,447 6/1963 H0511 s9-1.7 3,134,330 5/1964 Baton 89-13 X BENJAMIN A. BORCHELT, Primary Examiner.

SAMUEL W. ENGLE, Examiner. 

1. A PROJECTILE FIRING DEVICE COMPRISING: A CYLINDRICAL GUIDE MEMBER, A BODY MEMBER HAVING A CYLINDRICAL AXIAL BORE IN ONE END THEREOF EXTENDING TO A CLOSED END WALL, SAID CYLINDRIAL GUIDE MEMBER BEING SLIDABLY DISPOSED WITHIN SAID AXIAL BORE IN A FLUID-TIGHT MANNER, A PISTON SLIDABLY DISPOSED WITHIN SAID AXIAL BORE BETWEEN SAID GUIDE MEMBER AND SAID CLOSED END WALL OF SAID BODY MEMBER AND BEING IN CONTACT WITH SAID GUIDE MEMBER, THE SPACE BETWEEN SAID PISTON AND SAID CLOSED END WALL FORMING AN EXTENSIBLE EXPLOSION CHAMBER, AN AUXILIARY PROJECTILE INCLUDING A CARTRIDGE CASE HAVING AN EXPLOSIVE CHARGE AND A BALL MEMBER, SAID AUXILIARY PROJECTILE BEING POSITIONED WITHIN SAID EXTENSIBLE EXPLOSION CHAMBER IN FORCEFUL CONTACT WITH SAID PISTON AND SAID CLOSED END WALL OF SAID BODY MEMBER, STRIKER MEANS FOR EXPLODING THE CHARGE IN SAID CARTRIDGE CASE, AND SAID BODY MEMBER INCLUDING AT LEAST ONE RADIAL APERTURE COMMUNICATING WITH SAID AXIAL BORE AT A POINT SPACED FROM SAID PISTON ON THE SIDE THEREOF REMOTE FROM SAID CLOSED END WALL SO AS TO EFFECT COMMUNICATION OF SAID RADIAL APERTURE WITH SAID EXTENSIBLE EXPLOSION CHAMBER ONLY AT A PREDETERMINED TIME AFTER EXPLOSION OF SAID CARTRIDGE CASE. 